The present invention relates to television technology, and more particularly to automated lip sync error correction using an embedded video source identifier to control an adjustable audio delay.
Audio-to-video (A/V) synchronization is not a new problem. Television sources (video and audio) most often start with their video and audio synchronized such that the audio signal associated with the video signal is created at the same time. One exception to this is a sporting event shot with a long focal-length lens where the audio is received at some distance with a directional microphone. Wireless cameras are sometimes used and possibly field or sub-switched with wired cameras. The wireless camera uses a compression coder/decoder that adds video delay relative to the audio and wired camera video. Since a separate microphone, not part of the wireless camera system, often picks up the audio near the source, there is an additional A/V delay when the wireless camera is switched in place of the wired camera. Additionally the video often undergoes digital processing over video frames, making it arrive even later relative to the audio. Without adding a separate audio delay, the result is the annoying television signal referred to as lip-sync error. This is particularly annoying when the video or action precedes the audio, as in the case described.
What is desired is a method for automated correction of audio-to-video (A/V) lip sync error where a separate microphone is used as the audio source for a plurality of video sources, each video source introducing a different video processing delay, in order to re-time the video and audio signals to a desired relationship.